Production of photographs in blueblack tones



Y or one of its tautomeric forms, wherein Y may be Patented Oct. 6, 1942 PRObUCTION OF PHOTOGRAPHS IN BLUE- BLACK TONES Fritz Dersch, Binghamton, and Newton Heimbach, Johnson City, N. Y., assignors to General Aniline & Film Co rporation, Binghamton,

N. Y., a corporation of Delaware No Drawing. Application October 15, 1940, Serial No. 361,278

13 Claims.

This invention relates to a method for producing developed silver pictures from silver halide emulsions, and more particularly to a method by which said developed pictures are produced with a blue-black tone. 7 v

Many organic compounds have been suggested from time to time for producing a blue toning. effect on silver chloride emulsions. Thus triazole, tetrazole, quinine and similar compounds have been employed for this purpose. Suchcompounds, however, have little or no effect on the tone of a silver bromide emulsion. Very few agents are mentioned in the literature as blue toners for bromide emulsions. A condensation product of cystine and formaldehyde has been suggested for this purpose, but this particular compound is known to cause serious fogging.

With this prior art in view, it is accordingly one object of the presentinvention to provide a new process for the production of blue-black tones in silver halide emulsions.

A further object is to provide a new class of blue toning agents for silver bromide emulsions which will not have a serious fogging effect.

Another object is to provide anew class of blue toning agents which may be incorporated directly into a light-sensitive silver halide emulsion.

An additional object is to provide such agents which may be added to a photographic developer.

Other objects and advantages of the present invention will be readily apparent from the following description.

We have found that the foregoing objects are accomplished by the use of a new class of compounds as blue toning agents for silver bromide emulsions. These compounds all contain the grouping II t CNHCY either oxygen, sulfur, or selenium, and wherein the dangling valences are supplied by at least one organic radical. These compounds accordingly correspond to one of the two following formulae:

or their tautomeric forms, wherein Y has the meaning given above, R1 and R2 are independent group corresponding to one of the following formulae ..Q alkyl alkyl -Q C R. R R. \R

R4, R5, R6, and R1 representing either hydrogen or an alkyl group. I

Although we do not wish to limit ourselves to any particular theory, it is our belief, based upon experience, that the blue-toning properties of these compounds are primarily due to the presence of the group.

mentioned above. It is accordingly immaterial, for blue-toning purposes, whether any particular group or groups may supply the unsatisfied valences in the above formula, provided such groups are organic in nature.

While all the compounds corresponding to the above formulae exhibit a definite blue toning effect on silver bromide emulsions when used in suflicient-ly large amounts, we have found that there is a slight tendency on the part of some of these compounds to produce fog, especially when they are incorporated in the emulsion layer itself.

0 pounds just mentioned in which the substitution similar or dissimilar alkyl groups, and R3 is a,

Surprisingly enough, however, this fogging tendency is largely avoided when one uses those compounds of the above class in which the carbon atom next to the carbonyl group has no labile hydrogenatoms, said hydrogen atoms being entirely replaced by organic groups. ferred form of our invention, we use the comon this a-carbon atom is accomplished by alkyl groups.

Typical compounds corresponding to the above formulae and included in this invention are accordingly the following:

(1) Methyl acetyldithiocarbamate 2) 2-mercapto-4-keto- 5,5 -dimethylthiazoli dine O=GNH l c=s (CH3): 8

In the pre- (3) 2-mercapto-4-keto-5,5-dimethyl oxazolidine =C-NH (4) 2-mercapto-4-keto-5-methyl-5-ethyl oxazolidine 'I'hOSe compounds'designated as 2, 3, 4, 5, and 'l are especially suitable and are typical of the preferred group of di-substituted compounds according to the invention.

In order that those persons skilled in the art may fully understand the purpose and scope of this invention, the following detailed examples are given:

Example I To one liter of a typical metol-hydroquinone developer is added 20 to 40 mg, of 2-mercapto- 4-keto-5,5'-dimethyl-oxazolidine. The preparation of this compound is described in Beilstein, vol. 2'7, p. 252 and may be shown by the following equation: I

The foregoing developer will produce blue-black tones in the silver image obtained from a normally warm-toned gelatin silver bromide emulsion.

Example II Instead of the compound used in Example I, 30-50 mg. of 2-mercapto-4-keto-5-methyl-5- ethyl-oxazolidine may be added to one liter of the developer. This compound is prepared by the method described in Example I, but with methyl ethyl ketone used in place of acetone. exposed gelatino silver bromide emulsion is treated with the above developer, the developed silver image will show a noticeable blue-black tone.

Example III To one liter of a metcl-hydroquinone developer is added 10-20 mg. of 2-mercapto-4-keto-tetra- If an hydro-1,3-thiazine, prepared by the action of reactions involved are the following:

' be interpreted in an ammonium dithiocarbamate on the appropriate halogen acid (Beilstein, vol. 27,-Supp. p. 312):

This developer will produce a blue-toned silver image from an exposed gelatino-silver bromide emulsion.

Example IV To one kilogram of a gelatin silver bromide emulsion is added 50 mg. or 2-mercapto-4-keto- 5,5 dimethyl-dihydro-1,3-thiazine prior to coating. This compound is prepared according to the method outlined in trimethylaceticacid (J. 925) is employed in place acid as a starting compound. Exposure and development of this emulsion will yield an image having a blue-black tone.

Example V To one kilogram of a gelatin silver bromide emulsion is added 50 mg. of 2-mercapto-4-keto- 5,5-dimethylthiazolidine in 50 cc. of alcohol just prior to coating. The preparation of thiscompound (and all the other thiazolidines) is similar to the method described under Example III, except that the appropriate a-halogen acid is used in place of the p-halogen acid as a starting component. In this case a-blOIIlO-iSOblltYllQ acid is employed. The tone of the e will be displaced toward the blue.

Example VI To one kilogram of a gelatin silver bromide emulsion is added 30-50 mg. of 2-mercapto-4- keto-5,5-dimethyl selenazolidine prior to coating. Thiscompound was prepared by the action 01! carbon disulfide on dimethyl-pseudoselenohydantoin under pressure. A similar reaction has been described for the preparation of 2-mercapto-4- keto-thiazolidine from pseudothiohydantoin (Beilstein, vol. 27, p. 243). The dimethyl-pseudoselenohydantoin is prepared according to the reaction described for the comparable pseudoselenohydantoin (Beilstein, vol. 27, p. 243). The

A. C. 8., Apr. 1940, p.

A blue-toned silver image will be obtained after exposure and development of this emulsion.

It will be apparent that the amounts of the foregoing agents mayvary slightly with difierent types of emulsions, required can readily be determined by a few simple tests. The examples are accordingly to illustrative rather than a limiting sense.- It will also be understood that these blue-toning agents are equally useful in connection with mixed emulsions which contain one or more additional silver halides, provided said emulsions contain a substantial amount of silver bromide. Thus, for example, these blue toners may be used with gelatino silver chlorotbromide emulsions in accordance with this invenion.

Example III, but p-chlorooi the e-iodopropionic developed silver imbut the optimum quantities Now therefore we claim:

.1. In a process for producing developed silver pictures in blue-black tones from silver halide emulsions containing a substantial amount of silver bromide, the improvement which comprises developing said emulsions in the presence of an organic compound selected from the class consisting of: (A) compounds corresponding to the formula I? i Ri-CNHGYR| and its tautomeric forms, wherein Y is a member selected from the group consisting of oxygen,

sulfur and selenium, and R1 and R: are members selected from the class consisting of independent similar alkyl groups and independent dissimilar alkyl groups; and (B) compounds corresponding to the formula Rs-Y and its tautomeric forms, wherein Y is a member selected from the group consisting of oxygen, sulfur and selenium, and R3 is a member selected from the class consistingof the groups and .-o alkyl 1 RI \Rt 126 R R4, R5, Re and R1 being members selected from the class consisting of hydrogen and alkyl groups.

3. A photographic material comprising a silver halide emulsion layer having a substantial amount of silver bromide therein and containing as a blue-toning agent an organic compound corresponding to the formula n and its tautomeric forms, wherein Y is a member selected from the class consisting of oxygen, sulfur and selenium, and wherein Re is a member selected from the class consisting of nuclear methylene and ethylene groups in which both hydrogen atoms of at least the carbon atom in a-DOSitiOD to the carbonyl group are replaced by separate alkyl groups.

4. A photographic material comprising'a gelatino silver halide emulsion layer having a substantial amount of silver bromide therein and containing 2-mercapto-4-keto-5,5-dimethylthiazolidine as a blue-toning agent.

5. A photographic material comprising a gelatino silver bromide emulsion containing from -30 to 50 mg. of 2-mercapto-4-keto-5,5-dimethylthiazolidine per kilogram of emulsion.

6. A photographic material comprising a geiatino silver halide emulsion layer having a substantial amount of silver bromide therein and containing 2-mercapto-4-keto-5,5-dimethyl dihydro-1,3-thiazine as a blue-toning agent.

7. A photographic material comprising a gelatino silver bromide emulsion containing from 30 to 50 mg. of 2-mercapto-4-keto-5,5-dimethyl dihydro-1,3-thiazine per kilogram of emulsion.

8. A photographic developer comprising de-: veloping agents and, as a blue-toning agent, an

organic compound corresponding to the formula (Jill.

R4, R5, R6 and R1 being members selected from the class consisting of hydrogen and alkyl groups.

9. A photographic developer comprising developing agents and, as a blue-toning agent, an organic compound and its tautomeric forms, wherein 'Y is a member selected'from the class consisting of oxygen, sulfur and selenium, and wherein R3 is a member selected from the class consisting of nuclear methylene and ethylene groups in which both hydrogen atoms of at least the carbon atom in a-position to the carbonyl group are replaced by separate alkyl groups.

10. A photographic developer comprising de- 'veloping agents and 2-mercapto-4-keto-5,5-dimethyl oxazolidine as a blue-toning agent.

11. A photographic developer comprising developing agents and 2-mercapto-4-keto-5,5-dimethylthiazolidine as a blue-toning agent.

12. A photographic developer comprising developing agents and 2-mercapto-4-keto-5,5-di methyldihydro-l,3-thiazine as a blue-toning agent.

13. A photographic material comprising a gelatino silver halide emulsion layer having a substantial amount of silver bromide therein and FRITZ DERSCH. NEWTON HEIMBACH. 

